JP4697524B2 - Active matrix liquid crystal display device - Google Patents

Description

  The present invention relates to an active matrix liquid crystal display device, and more particularly to an active matrix liquid crystal display device using a thin film transistor (hereinafter referred to as “TFT”) as a semiconductor switching element, and provided with means for preventing TFT breakdown due to static electricity. The present invention also relates to an active matrix liquid crystal display device.

  In general, liquid crystal display devices are characterized by thinness, light weight and low power consumption. In particular, thin film transistor type active matrix liquid crystal display devices are widely used from mobile phones and portable terminals to large televisions.

First, a general configuration of a conventional active matrix liquid crystal display device is shown in FIG. 4 which is a plan view of several pixel portions, and a schematic equivalent circuit diagram corresponding to several pixels in FIG. 5 and FIG. This will be briefly described with reference to FIG. 6 which is a sectional view. The conventional liquid crystal display device 10A is provided for each region surrounded by scanning lines X1, X2,... Xn and signal lines Y1, Y2,. pixel electrodes 12 are provided, the pixel electrode 12 are equivalently represented by a liquid crystal capacitance C _LC in FIG. Usually the liquid crystal capacitance C _LC auxiliary capacitance Cs formed by the auxiliary capacitance electrodes 13 are connected in parallel. One end of the liquid crystal capacitance C _LC is connected to the switching transistor 14 for driving, the other end is connected to a common electrode 16 provided through the color filter layer CF to the second light-transmitting substrate 15 a predetermined Common potential Vc is applied.

The switching transistor 14 comprises an insulated gate field effect type thin film transistor TFT (Thin Film Transistor), and its source electrode S is connected to signal lines Y1, Y2,. D is connected to one end of the liquid crystal capacitance C _LC, i.e., the pixel electrode 12. Further, the gate electrode G of the switching transistor 14 is connected to the scanning lines X1, X2,... Xn so that a gate pulse Vg having a predetermined voltage is applied.

An alignment film (not shown) is provided on the surface of each of the pixel electrode 12 and the common electrode 16, and between the first light-transmitting substrate 11 and the second light-transmitting substrate 15. Liquid crystal 17 is enclosed. Reference numerals 18 and 19 denote insulating films made of SiO ₂ or SiN, respectively, and reference numeral 20 denotes an a-Si layer. The plurality of scanning lines X1, X2,... Xn and the signal lines Y1, Y2,... Ym are drawn in two directions or one direction of the frame portion of the substrate (peripheral portion of the substrate), A scanning line input terminal 21 and a signal line input terminal 22 are provided.

  The active matrix liquid crystal display device having such a structure has been manufactured from a small size for a mobile phone to a large size of about 40 inches (about 102 cm) to 50 inches (about 127 cm) diagonal. ing. However, in the liquid crystal display device, when static electricity enters the display region in the manufacturing process, a display defect occurs when the liquid crystal display device is completed. Especially in small and medium-sized models, static electricity defects are more likely to occur as the resolution becomes higher. Static electricity is generated only by contact with other objects in the manufacturing process and when the panel is transported. Further, when the alignment film is rubbed, static electricity is most likely to occur due to friction. Therefore, in the manufacturing technical field of liquid crystal display devices, it is particularly urgent to prevent display defects due to static electricity.

  Several techniques for preventing the occurrence of pixel defects due to static electricity are also known. For example, in the invention of the active matrix type liquid crystal display device 30 disclosed in Patent Document 1 below, as shown in FIG. 7, a striped gate signal line 31 on a substrate and a striped source signal orthogonal to the gate signal line 31 are formed. A line 32; a switching element TFT provided in the vicinity of the intersection; and a plurality of pixel electrodes connected to the switching element TFT and formed in a matrix. The pixel electrode is within the effective display area. The display pixel electrode 33A that is provided and contributes to display and the dummy pixel electrode 33B that is provided in the non-effective display area and does not contribute to display are provided. The gate signal line 34 for driving the dummy pixel electrode 33B is connected to the effective display area. It is formed by branching from the gate signal line 31. Furthermore, Patent Document 1 below also suggests providing a plurality of dummy pixel electrodes 33B in order to reliably protect the effective display area.

  That is, the liquid crystal display device 30 has a dummy pixel electrode 33B provided in the ineffective display area when static electricity enters through the first or second signal lines 31 and 32 during the manufacturing process of the liquid crystal display device. Since the switching element connected to is preferentially destroyed, the switching element connected to the display pixel electrode in the effective display area can be protected.

  On the other hand, as shown in FIG. 8, the liquid crystal display device 40 disclosed in the following Patent Document 2 includes a scanning line 41 and a signal line 42 formed so as to be orthogonal to each other, and the scanning line 41 and the signal line 42. A switching element TFT formed at the intersection and a plurality of display pixel electrodes 43A connected to the switching element TFT and driven and controlled by signals supplied from the scanning line 41 and the signal line 42 are formed in the effective display area. On the other hand, a plurality of dummy pixel electrodes 43B separated from the scanning lines 41 and the signal lines 42 are formed in the periphery of the effective display area, and an additional auxiliary capacitance electrode 44 is formed so as to face the dummy pixel electrodes 43B. It is.

That is, in the liquid crystal display device 40, when static electricity enters through the first or second signal lines 41 and 42 during the manufacturing process of the liquid crystal display device, the dummy pixel electrode 43B provided in the ineffective display region. Since the charged static electricity is discharged through the additional auxiliary capacitance electrode 44 or the other auxiliary capacitance electrode 45, the switching element TFT connected to the display pixel electrode 43A in the effective display area. It becomes possible to protect.
Japanese Patent Application Laid-Open No. 10-213816 (Claims, paragraphs [0029] to [0034], [0039], [0048], FIG. 2) Japanese Patent Laid-Open No. 11-052427 (Claims, FIG. 1)

  However, in the liquid crystal display device 30 disclosed in Patent Document 1, since only one dummy pixel electrode 33B is provided for the gate signal line 31 or the source signal line 32, the dummy pixel electrode 33B is once formed by static electricity. When the switching element TFT is destroyed, the dummy pixel electrode 33B loses its ability. Therefore, when static electricity enters again, the switching element TFT of the pixel electrode 33A in the display area may be destroyed. There is. In other words, when manufacturing a liquid crystal display device, static electricity is generated not only when the alignment film is rubbed but also when the panel is transported. There is a possibility that static electricity may infiltrate many times, but the liquid crystal display device 30 disclosed in Patent Document 1 may not be able to cope with such many times of electrostatic intrusion.

  In the upper patent document 1, it is suggested that a plurality of dummy pixel electrodes 33B are provided in order to reliably protect the effective display area (see paragraph [0039]). Since the pixel electrode 33A is not as large as or larger than the pixel electrode 33A in the effective display area (see claim 3, paragraph [0048]), there is a problem that the ineffective display area becomes large.

  Further, in the liquid crystal display device 40 disclosed in Patent Document 2, when static electricity enters through the scanning lines 41 and the signal lines 42 during the manufacturing process of the liquid crystal display device, a dummy provided in the ineffective display area. Although the pixel electrode 43B is charged, the dummy pixel electrode 43B functions as a capacitor because it is separated from the scanning line 41 and the signal line 42. Therefore, the static electricity is added to the additional auxiliary capacitance electrode 44 or the like. There is a possibility that the switching element TFT connected to the pixel electrode 43A in the effective display area is subjected to electrostatic breakdown before entering the pixel electrode 43A in the effective display area before discharging through the auxiliary capacitance electrode 45. To do.

  The inventor of the present application has conducted various studies to solve the problems of the technology for preventing electrostatic breakdown of the switching element connected to the pixel electrode in the effective display area due to static electricity in the conventional example as described above. In order to effectively discharge static electricity that has entered from the outside, if only a configuration similar to the switching element TFT connected to the pixel electrode in the effective display area is provided as a dummy pixel provided in the ineffective display area, the dummy pixel electrode Even if the area is extremely small, the switching element of this dummy pixel preferentially causes electrostatic breakdown, so there is no risk of static electricity entering the effective display area, effectively protecting the switching element connected to the pixel electrode. In addition, since about 10 times as many dummy pixels can be provided in the same area as the pixel electrode of the conventional effective display area. Without increasing the area of the non-effective display region, in a large number of times static electricity entering found that it is possible to cope is of the present invention has been completed.

  That is, an object of the present invention is to provide a liquid crystal display device in which a large number of dummy pixel electrodes are provided without increasing the area of the ineffective display area and which can cope with a large number of electrostatic intrusions from the terminal side.

The above object of the present invention can be achieved by the following configurations. That is, the active matrix liquid crystal display device of the present invention includes a substrate, a plurality of signal lines arranged on the substrate, a plurality of scanning lines arranged on the substrate, and an effective display area contributing to display. In the active matrix type liquid crystal display device comprising a non-effective display area that does not contribute to display around the effective display area, the signal lines and the scanning lines are arranged in a matrix, and in the effective display area, One transistor is formed in a region surrounded by the adjacent signal line and the adjacent scanning line, and the ineffective display region is surrounded by the adjacent signal line and the adjacent scanning line. A plurality of transistors are formed in the region, a display pixel electrode is connected to the transistors in the effective display region, and a plurality of transistors in the ineffective display region are connected. Each dummy pixel electrode is connected to the static area of the dummy pixel electrode, wherein the at most 1/2 of the area of the display pixel electrode.

In the above active matrix liquid crystal display device, the area of the dummy pixel electrode is 1/2 or less and 1/20 or more of the area of the display pixel electrode.

Further, in an active matrix type liquid crystal display device described above, the switching transistor connected to the dummy pixel electrode is connected to the signal line to the source electrode, each parallel, a gate electrode is connected to the scanning line in parallel It is characterized by that.

In the above active matrix liquid crystal display device, the switching transistor connected to the dummy pixel electrode is smaller than the channel width and channel length of the switching transistor connected to the display pixel electrode. It is characterized by.

By providing the above configuration, the present invention has the following excellent effects. That is , since a plurality of dummy pixels having extremely small switching transistors are provided in parallel in the ineffective display area, even if static electricity enters from the terminal side, the switching transistors of the dummy pixels are preferentially sacrificed and sparked. Since static electricity can be released, a liquid crystal display device with less possibility of static electricity reaching the display area and few display defects can be obtained. In addition, since a plurality of dummy pixel electrodes are provided in parallel, it is possible to cope with a plurality of times of electrostatic intrusion, and therefore there is very little possibility that display pixels in the display area are electrostatically destroyed during the manufacturing process. Become.

Further, conductive since the vapor manner one dummy pixel electrode corresponds to the display pixel electrode one minute, since the size of one dummy pixel electrode is 1/2 or less 1/20 or more of the display pixel electrodes, the area When viewed from the viewpoint, since 2 to 15 dummy pixels can be arranged in the area of one display pixel, the ineffective display area (frame portion) does not become wide. In addition, since many sacrificed dummy pixels are connected from the input terminal, even if it is sparked in order from the end portion, the number of times to reach the display area can be increased, so that it reaches the effective display area. Can be reduced.

  If the area of the dummy pixel electrode exceeds 1/2 of the area of the display pixel electrode, it is not preferable because the number of dummy pixels provided in parallel cannot be increased unless the ineffective display area is widened. If it is less than / 20, the amount of static electricity that can flow to each dummy pixel electrode is reduced, which is not preferable. A more preferable area of the dummy pixel electrode is 1/5 or less and 1/15 or more of the area of the display pixel electrode.

Further, it is possible to arrange the switching transistors connected to a number of dummy pixel electrodes in small a surface area, since the size of the dummy pixel can be reduced, the non-effective display area (frame portion) that is wide Absent.

Further, the switching transistor connected to the dummy pixels for easily broken electrostatic than the switching transistor connected to the display pixel electrodes are connected to reliably dummy pixel electrode be static from the outside penetrates Since the switching transistor is electrostatically destroyed, the possibility of static electricity entering the effective display area is reduced.

  Hereinafter, embodiments of an active matrix type liquid crystal display device according to the present invention will be described in detail with reference to the drawings. However, the embodiment described below exemplifies a transflective liquid crystal display device as an active matrix liquid crystal display device for embodying the technical idea of the present invention. The present invention is not intended to be specified as a display device, and the present invention can be equally applied to a variety of modifications without departing from the technical idea shown in the claims. 1 is an enlarged plan view of the vicinity of the effective display area and the non-effective display area of the transflective liquid crystal display device according to the embodiment, FIG. 2 is an enlarged plan view of area A in FIG. 1, and FIG. It is BB sectional drawing of FIG. 1 to 3, the same reference numerals are assigned to the same components as those of the conventional liquid crystal display device shown in FIGS.

  The transflective liquid crystal display device 10 according to the embodiment includes scanning lines X1, X2,... Xn, Xn + 1, Xn + 2 and signal lines Y1, Y2,. -Ym is provided. Among these, the area surrounded by the scanning lines X1, X2,... Xn and the signal lines Y1, Y2,... Ym is an effective display area, and the scanning lines Xn, Xn + 1, Xn + 2 and the signal lines Y1, Y2,. A region surrounded by Ym is an ineffective display region.

  In this effective display area, a pixel electrode including the pixel electrode 12 and the reflective electrode 25 that contribute to display is provided for each area surrounded by each scanning line and signal line. The switching transistor 14 is made of a TFT, the source electrode S is connected to the signal lines Y1, Y2,... Ym, the gate electrode G is connected to the scanning lines X1, X2,. Is connected to the pixel electrode 12 and to the reflective electrode 25 through a contact hole (not shown). In addition, an auxiliary capacitance electrode 13 is provided below the drain electrode D. Since the operating principle of these transflective liquid crystal display devices 10 is already well known, detailed description thereof will be omitted.

  On the other hand, the transflective liquid crystal display device 10 according to the embodiment is a switching composed of TFTs that do not contribute to display in an ineffective display region surrounded by scanning lines Xn, Xn + 1, Xn + 2 and signal lines Y1, Y2,. A plurality of dummy pixels each having a transistor 26 and a dummy pixel electrode 27 are provided for each signal line Y1, Y2,.

  The source electrode S of the switching transistor 26 of the dummy pixel is connected in parallel for each signal line Y1, Y2,... Ym, the gate electrode G is connected in parallel for each scanning line Xn + 1, Xn + 2, and further the drain electrode. As shown in FIG. 3, D is connected to a dummy pixel electrode 27 provided on the interlayer film 29 through a contact hole 28. The switching transistor 26 of the dummy pixel is smaller than the channel width and channel length of the switching transistor 14 connected to the display pixel electrode, and thereby the switching transistor 14 connected to the display pixel electrode. It is designed to be preferentially destroyed by electrostatic discharge.

  The area of the dummy pixel electrode 27 is smaller than the area of the electrode contributing to display for one pixel in the effective display area, that is, the sum of the area of the pixel electrode 12 and the area of the reflective electrode 25. If the area of the dummy pixel electrode 27 is too large, the number of dummy pixels provided in parallel cannot be increased unless the non-effective display area is widened. If the area is too small, the dummy pixel electrode 27 can flow to one dummy pixel. Since the amount of static electricity is reduced, it is preferable that the area of the display pixel electrode composed of the pixel electrode 12 and the reflective electrode 25 in the effective display region is 1/2 or less and 1/20 or more. The area of the dummy pixel electrode 27 is more preferably 1/5 or less and 1/15 or more of the area of the display pixel electrode in the effective display area. In FIG. 1, the area of each dummy pixel electrode 27 is set to 1/10 of the area of the display pixel electrode in the effective display area, and 10 each between the scanning lines Xn and Xn + 1 and between Xn + 1 and Xn + 2. A total of 20 are shown.

In the transflective liquid crystal display device 10 according to this embodiment provided with the dummy pixel having such a configuration, when static electricity enters from the signal line input terminal 22, the dummy pixel closest to the signal line input terminal 22 is also selected. switching transistor 26 ₁ discharges the static electricity by causing an electrostatic breakdown. Thereafter, the static electricity entering from the signal line input terminal 22 again to discharge the static electricity by the switching transistor 26 ₂ of the first next to the switching transistor 26 ₁ of the dummy pixel that caused static discharge electrostatic breakdown. For this reason, in the manufacturing process of the transflective liquid crystal display device 10, electrostatic intrusion that destroys the switching transistor 14 in the effective display area can be allowed up to 20 times, so that display defects substantially occur. Thus, a transflective liquid crystal display device 10 free from the above is obtained.

  In this embodiment, a transflective liquid crystal display device has been described as an example. However, the present invention is not limited to this, and is applied to a transmissive liquid crystal display device and further to a reflective liquid crystal display device. be able to.

FIG. 3 is an enlarged plan view of the vicinity of an effective display area and an ineffective display area of a transflective liquid crystal display device according to an example. FIG. 2 is an enlarged plan view of a region A in FIG. 1. It is BB sectional drawing of FIG. It is a top view which shows the structure of several pixel parts of the conventional active matrix type liquid crystal display device. FIG. 6 is a schematic equivalent circuit diagram for several pixels of a conventional active matrix liquid crystal display device. It is ZZ sectional drawing of FIG. It is a top view for several pixels of the active matrix type liquid crystal display device which has the conventional dummy pixel electrode. It is a top view for several pixels of the active matrix type liquid crystal display device which has another conventional dummy pixel electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transflective liquid crystal display device 10A Liquid crystal display device 11 1st translucent board | substrate 12 Pixel electrode 13 Auxiliary capacity electrode 14 Switching transistor 15 2nd translucent board | substrate 16 Common electrode 17 Liquid crystal 18 and 19 Insulating film 20 a- Si layers 21 and 22 Input terminal 25 Reflective electrode 26 Switching transistor 27 of dummy pixel Dummy pixel electrode 28 Contact hole 29 Interlayer film

Claims (4)

A substrate,
A plurality of signal lines arranged on the substrate;
A plurality of scanning lines disposed on the substrate;
An effective display area that contributes to the display;
In an active matrix liquid crystal display device comprising: an ineffective display area that does not contribute to display around the effective display area;
The signal lines and the scanning lines are arranged in a matrix,
In the effective display region, one transistor is formed in a region surrounded by the adjacent signal line and the adjacent scanning line,
In the non-effective display area, a plurality of transistors are formed in an area surrounded by the adjacent signal line and the adjacent scanning line ,
A display pixel electrode is connected to the transistor in the effective display area,
A dummy pixel electrode is connected to each of the plurality of transistors in the non-effective display area,
An active matrix liquid crystal display device , wherein the area of the dummy pixel electrode is ½ or less of the area of the display pixel electrode . Area before Symbol dummy pixel electrodes, an active matrix type liquid crystal display device according to claim 1, wherein the at least 1/20 of the area of the display pixel electrode. 3. The active matrix liquid crystal display device according to claim 1, wherein source electrodes of the plurality of transistors in the ineffective display area are connected in parallel to the signal lines. 4. The non-effective multiple transistors of the display area, according to claim 1 active matrix type according to any one of the three liquid crystal, characterized in that is smaller than the channel width and channel length of the transistor in the effective display region Display device.

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